This application is based on and claims the priority date of European Patent Application No. 02 012 068.9, filed on May 31, 2002.
The invention relates to a method and an associated apparatus for detaching an embedded manhole frame.
To replace the manhole frames of manhole covers, e.g., in case of damage, the prior art calls for breaking up the asphalt or concrete road surface in which the manhole frame is embedded, preferably with pneumatic tools, until the manhole frame is easily accessible with the tools. After separating the manhole frame from the asphalt or concrete road surface and detaching it from the manhole cone or brickwork, the manhole frame can be lifted out manually, often piece-by-piece. The manhole cone can be damaged easily during this operation as a result of scraping, which reduces its load-carrying capability. For a high-quality reconstruction, the area where the road surface is broken up must be freed up to the manhole cone and the manhole cone must then be reconstructed, starting with the upper cone edge. The large area of repair and the considerable expenditure for the repair is a disadvantage.
Accordingly, it is the object of the present invention to provide a method for detaching an embedded manhole frame and a device that is particularly suitable for realizing this method. The method calls for a quick and low-cost removal of the manhole frame, without having to free a larger area around the manhole frame and the manhole cone, and without damaging the manhole cone section adjacent to the manhole frame. The method and device should lend themselves to a high degree of automation.
The above object generally is achieved according to a first aspect of the invention by a method for detaching a manhole frame embedded in a road surface wherein the manhole frame is horizontally detached, starting from the inside, with the aid of a rotating cutting blade that performs eccentric circumferential runs along the inside of the manhole frame.
As a result of the horizontal cut made to the manhole frame from the inside, which is realized with a rotating cutting blade that performs circumferential runs around the circumference at increasing depth up to the manhole frame cone wall on the outside, the manhole frame section can be cut off quickly without having to free it on the outside. There is no danger of damage to the remaining manhole cone due to the smooth cutting, so that the reconstruction is made easier. Since the manhole frame is not cut into smaller pieces, it can then be lifted out in one piece with the aid of a machine once it has been separated on the outside from the connection to the asphalt/concrete road surface. It is particularly advantageous if the manhole frame is separated from the asphalt/concrete road surface and the deeper layers by drilling concentrically around the outside of the manhole frame, up to the depth of the horizontal cut and, if necessary, slightly past it. As a result, uncontrolled retractions and expansions in the asphalt road surface are avoided during this operation. The manhole frame can be replaced without considerable preliminary work or a subsequent reworking of a construction site surrounding the manhole frame and a repaired frame can be released immediately for road traffic.
Preferably, the horizontal cut into the manhole frame is made during several successive circumferential runs of the cutting blade, meaning partial cuts with increasing depth toward the outside of the manhole frame. The cutting depth of each partial run can be adjusted for the essentially circumferential run along the cylindrical inside space of the manhole frame.
The above object generally is achieved according to a second aspect of the invention by a device for detaching an embedded manhole frame, according to the above-mentioned method, with the device generally comprising a rotating cutting blade that is mounted on a turntable such that it can be adjusted horizontally eccentric to the axis of the turntable and that also can be adjusted vertically adjustable. The turntable mounted for rotation on a mounting support with fastening elements that are suitable for locking in place the mounting support inside the manhole frame.
The device can have a compact enough design to be deposited easily with a truck-mounted loading crane at the place of use, above a manhole frame. The detaching device thus requires little road space. If the cutting blade is operated, e.g., made to rotate, preferably with a hydraulic drive motor, the hydraulic system of the truck, which otherwise functions to activate the loading crane, can be used for driving the cutting blade. In further detail, the detaching device with its mounting support is placed over the manhole frame onto the asphalt/concrete road surface, such that the manhole frame is positioned concentrically within the preferably round mounting support. The mounting support is then attached with its fixation or fastening elements to the manhole frame, wherein an additional centering can occur. The cutting blade is subsequently lowered into the manhole frame up to the intended location of detachment from the manhole cone or brickwork. The cutting blade is adjusted eccentrically with respect to the turntable that is mounted for rotation on the mounting support, wherein the cutting blade pushes from the inside against the manhole cone or the brickwork. Flushing water is preferably fed into the rotating cutting blade, and the rotating cutting blade performs a circumferential run along the cylindrical inside wall of the manhole cone or brickwork via the turntable, in particular via a simple manual guide rod assembly. In the process, the cutting blade cuts into the manhole cone or the brickwork. The circumferential runs of the cutting blade along the inside wall are repeated with constant readjusting of the cutting blade until the manhole frame/cone wall is cut through completely up to the outside edge. Several circumferential runs of the cutting blade are thus made with increasing cutting depth toward the outside. With this device for detaching the manhole frame, the above-described functions can be realized reliably. The device is distinguished by its simplicity and robustness and can be automated, in particular for adjusting the cutting blade.
Since the detaching device with the cutting blade is placed against the inside wall of the manhole cone or brickwork, it is not necessary to expose the manhole frame, the manhole cone or the brickwork on the outside.
The subsequent exposure of the manhole frame outside can be reduced to a minimum, so that the manhole frame that is horizontally detached in one piece, or the drill chips, can be lifted out of the pit with the aid of a hoisting device. Thus, the exposure is required only up to the depth of the horizontal cutting location. A hydraulic drill can be used for this reduced exposure, which is suitable for drilling a clearance space around the outside circumference of and concentric to the manhole frame.
It must further be emphasized here that the detaching device does not damage the regions of the manhole cone or brickwork below the cutting location because of the horizontal cutting or detaching method. No repair or reconstruction work on the upper cone edge is therefore necessary.
Details of the features of the detaching device, with its uncomplicated design, generally include a rotating positioning of the cutting blade mounted in a vertically oriented spacer tube, a pivoting arm provided with a first section and, at a distance thereto, a second section, a vertical adjustment of the spacer tube on a first section of the pivoting arm and the positioning of the second section of the pivoting arm such that it can pivot on the turntable for adjusting the eccentricity at the cutting location. The spacer tube in this case is advantageously provided with a device for locking in place the height or depth adjustment of the cutting blade. By pivoting the pivoting arm around its bearing location on the turntable, the eccentricity of the spacer tube and thus the cutting blade is adjusted, so that the cutting blade fits under pressure against the inside or brickwork of the manhole cone.
According to a further feature of the invention, a simple and robust threaded rod is provided for adjusting the eccentricity. This rod, on the one hand, is engaged in a member on the second section of the pivoting arm and, on the other hand, has one end pivotally mounted on the turntable. The threaded rod can be adjusted simply by turning it, thus eccentrically adjusting the pivoting arm as well as the spacer tube and the cutting blade. While lowering the cutting blade, meaning during the height adjustment, this blade is oriented nearly concentric inside the manhole frame. At the operating depth, the cutting blade is then moved eccentrically against the inside wall of the manhole cone or the brickwork.
A hydraulic adjustment of the pivoting arm is also possible, which can furthermore occur automatically.
For a sensitive, but also strong guidance during the circumferential run of the cutting blade for the horizontal cutting operation, a manual guide rod assembly is attached in an uncomplicated manner to the turntable. The guide rod assembly can be designed, for example, to resemble a nearly reversed U-shape, which is bent at an angle to form a lever arm that can be used to manually exert a torque onto the turntable.
According to a further feature of the invention, the turntable can be prevented from turning in one rotational or circumferential run direction by using at least one detent pawl that is positioned on the mounting support for the turntable and engages a toothed edge of the turntable. Even a high torque exerted by the cutting blade during the cutting operation onto the turntable can be absorbed safely in this manner.
The rotational direction of the cutting blade can be reversed, for example, with a hydraulic control unit for a quick realization of the horizontal cut with increasing cutting depth.
According to a still further feature, the mounting support that carries the turntable comprises, in an uncomplicated manner, a ring that can be secured with screws inside the manhole frame and on which the turntable is positioned for concentric rotation.
The invention is explained in the following with the aid of an exemplary embodiment of the detaching device and with the aid of seven Figures.